261220011 has 16 divisors (see below), whose sum is σ = 397149984. Its totient is φ = 151294464.

The previous prime is 261220009. The next prime is 261220019. The reversal of 261220011 is 110022162.

It is not a de Polignac number, because 261220011 - 2¹ = 261220009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261220019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196336 + ... + 197661.

It is an arithmetic number, because the mean of its divisors is an integer number (24821874).

Almost surely, 2^261220011 is an apocalyptic number.

261220011 is a deficient number, since it is larger than the sum of its proper divisors (135929973).

261220011 is a wasteful number, since it uses less digits than its factorization.

261220011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394030.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 261220011 is about 16162.3021565617. The cubic root of 261220011 is about 639.2471706239.

Adding to 261220011 its reverse (110022162), we get a palindrome (371242173).

The spelling of 261220011 in words is "two hundred sixty-one million, two hundred twenty thousand, eleven".